Ring Vortex questions

[P3CFE]

Just a question about the presentation of the Ring vortex in DCS.

 

With Mi8 in hover with load descending with 200 ft/min it went into vortex ring state on its own.

 

This makes flying a helicopter far more risky than I thought.

I would not want to get in such a heli in real life...much to dangerous !!

I also think the helicopter would not be certified for flight because of being to unstable and unreliable.

 

The huey is more forgiving but here also I got my doubts about the onset parameters of vortex.

 

Is it really this critical in real life ?

Does somebody really know ?

[Cibit]

The Mi-8 has had lots of input from real life mi-8 pilots. They all believe it is realistically moddeled

[Art-J]

Was it really correctly indicated descent rate in fpm? I don't use cockpit mods, staying with default instruments and metric units. In real Mi-8, You're not supposed to descent in hover faster than 3 m/s, with collective lower than 3 degrees.

 

It's been always working perfectly in DCS Hip. I haven't flown the thing much in 1.5.4, because of trim bug. During a flight or two, the FM didn't seem to have changed, though.

 

200 fpm is about 1 m/s, so You should be more than enough on the safe side.

[AG-51_Razor]

I had a very hard time getting used to the Vortex Ring State (Settling With Power) as it is modeled by Belsimtek for the Mi-8. But that was before I was made aware of the fact that the vertical speed indicator is in Meters/Second!! Not Feet/Minute. That makes for a huge difference. Additionally, as long as you are not below ETL (effective translational lift) speed, it is pretty benign. So, although I still feel like the modeling of it is a bit arbitrary, it is still pretty well done for a desktop simulator. The best advice I can give you is to keep one eye on the vertical speed indicator and the other one on your airspeed indicator. When you go through ETL, the a/c with rumble and shake, and if you have a vertical speed of less than 3.00m/s - correcting to zero - then you will not have a problem with the vortex ring state.

 

I have found that, due to the lack of depth perception in a 2D monitor, it is very difficult to determine your height above an object or the ground even, so the most common error made during approaches is to overshoot your target, and end up at a hover well out of ground effect above or beyond your point of intended landing. The hardest thing for me to do is to try to stay in the hover and descend to a landing from a 100 meters or so. It would be better to go around and descend during the turn.:thumbup:

 

It's not exactly right in my opinion, but it is by far the best you'll ever encounter outside of a professional Level D simulator!! :thumbup:

Edited July 20, 2016 by PilotMi8

[Art-J]

and if you have a vertical speed of less than 300m/s - correcting to zero - then you will not have a problem with the vortex ring state.

 

Hmmm.... 300 m/s is about the speed of an average handgun bullet innit :D ? He might not exactly avoid problems with VRS at this speed, but it's certainly good figure to keep the chopper from going supersonic and breaking-up to pieces ;) :D.

[NeilWillis]

Errata - delete the two zeros.

[AG-51_Razor]

DOH :doh:

 

What NeilWillis said!

[P3CFE]

Oke thanks you all, that was a stupid mistake I made.

 

I should have read 2 m/s, that is close to 400 ft/min, double of what I thought.

 

Vortex makes sens again :)

 

That makes me the part of the heli that is dangerous :(

[Cibit]

Keep at it mate it will come good soon :)

[P3CFE]

Thanks Cibit,

 

And I will...its a great module,...I will gladly spend time to tame this MI-8.

 

Cheers

[Flamin_Squirrel]

Fly your approaches shallow as if you were in a fixed wing aircraft, and aim to reduce your speed to 0 add you reach the ground. It should make things easier.

[Hook47]

Most of my time in a rotary wing is in a CH-47D Chinook, and VRS was a very real concern there. I've always felt DCS does an excellent job simulating these helicopter specific dynamics in ways other sims don't even come close. After flying under the Rift, I echo the above statement 10 fold. It is pretty much a 1 to 1 representation of real helo flying- actually puts some of the U.S. Army helo sims to shame!

[Socket7]

I love the way the MI-8 enters VRS. After many hours flying it you can actually feel it start to flounder and claw at the air right before it begins plummeting to the ground beyond the hope of any additional collective pulling you out of it.

 

Aside from a lot of practice, the best way to avoid VRS is not descending while below ETL. Keep yourself moving forward and practice flaring to a stop and hover just above your landing spot rather than flying over, hovering, and descending.

[Deezle]

Yeah be aware, being a Russian aircraft, everything is metric. Try to use the Dopper hover indicator when possible over the VVI.

 

One thing that's really helpful for staying out of VRS is SimShaker combined with a buttkicker or jetseat. Getting that's vibratory feedback is huge, can't fly without it anymore.

[Vitormouraa]

The Mi-8 has had lots of input from real life mi-8 pilots. They all believe it is realistically moddeled

 

It really is. Reading this from DCS website, you can easily see many and many of the RL features are simulated.

 

 

Flight Model

Helicopter velocity is determined using complete equations that calculate the forces and moments not only at the fuselage center of gravity (CG), but also acting on the turning rotors, which include the flapping motions of the rotor blades. This makes it possible to model all of the dynamic effects specific to helicopter flight.

 

The aerodynamic forces acting on the helicopter model are derived as a summation of the parameters of its individual elements: main and tail rotors, fuselage, vertical stabilizer, horizontal stabilizer, pylons, and undercarriage. Each of these elements is positioned and orientated individually within the airframe's local coordinate system and has its own aerodynamic characteristics.

 

The aerodynamic characteristics of each model element are pre-calculated with special software using numerical methods. In determining the forces and moments acting on the main and tail rotors, the calculations include the axial and longitudinal components of airflow speed, blade pitch, rotor angular velocities, airflow parameters, and blade inertia characteristics.

 

The aerodynamic forces acting on each model element are determined according to its pre-calculated characteristics in its own coordinate system. This includes local airflow velocity changes in the vicinity of the element as induced by other model elements.

 

Each element has a damage/destruction capacity that affects the lifting and center of gravity calculations of the model. Damage can be affected either by aerodynamic force or by physical contact with the ground or other objects. Ground and object contact is modeled using a system of rigid body points.

 

The detailed, real-time modeling of the dynamics involved with the main and tail rotors, fuselage, empennage, and other elements of the airframe produces flight characteristics that closely match those of the real helicopter and make it possible to naturally induce and closely model important flight conditions and effects like torque-induced yaw, translational lift, translating tendency, rotor overspeed and droop, retreating blade stall, autorotation, settling with power (vortex ring state), etc.

 

The Mi-8MTV2 simulation was developed under the management of an experienced Mi-8 pilot and with reference to a wealth of aircraft documentation and further testing by pilots and other subject matter experts to ensure the accuracy of the model's performance.

 

Edited July 21, 2016 by Vitormouraa

[Enduro14]

Yeah be aware, being a Russian aircraft, everything is metric. Try to use the Dopper hover indicator when possible over the VVI.

 

One thing that's really helpful for staying out of VRS is SimShaker combined with a buttkicker or jetseat. Getting that's vibratory feedback is huge, can't fly without it anymore.

 

Fact! i cant fly without it either so much better flying helis with it

[Cibit]

Agreed the Jetseat makes me go close to VRS just to get those vibes man:megalol:

But it is true the extra sensory input really helps, can't wait till VR is more affordable:)

 

There are some good tips in this thread to help lessen the learning curve

http://forums.eagle.ru/showthread.php?t=155017

[P3CFE]

Great.....

 

Starting thist thread costs me...

 

You made me buy the Jet seat :)

[Cibit]

Well you won't regret it. But yeah this SIM business costs money:P

[Rogue Trooper]

Great.....

 

Starting thist thread costs me...

 

You made me buy the Jet seat :)

 

You will love it, personally I crank up all the vibration settings but the vortex ring state is a real nice vibration and occurs quickly.

Seat of pants flyiing?... almost!

Edited July 22, 2016 by Rogue Trooper

[Rogue Trooper]

Agreed the Jetseat makes me go close to VRS just to get those vibes man:megalol:

But it is true the extra sensory input really helps, can't wait till VR is more affordable:)

 

There are some good tips in this thread to help lessen the learning curve

http://forums.eagle.ru/showthread.php?t=155017

 

Better Rez and more peripheral vision for me... I can't wait.:D